A Long Term Evolution (LTE) system supports a time division duplex (TDD) mode, that is, different timeslots of a same frequency are used for an uplink and a downlink. To meet requirements of different uplink-downlink asymmetric services, in an LTE TDD system, an uplink-downlink configuration may be configured in a semi-static manner according to a service type. However, the uplink-downlink configuration that is used is configured in a semi-static manner and cannot be changed dynamically. Therefore, the current uplink-downlink configuration does not match transient uplink and downlink service volumes. As a result, resources cannot be used effectively. The problem is especially serious for a cell with a relatively small quantity of users. In the prior art, to resolve the foregoing problem, a concept of a dynamic TDD uplink-downlink subframe configuration is introduced. That is, some flexible subframes are configured in a radio frame, where each flexible subframe may be dynamically configured as an uplink subframe or a downlink subframe.
In the prior art, when sending an uplink signal, user equipment (UE) needs to configure transmit power of the uplink signal according to a transmit power control command (TPC) notified by a base station, so that the uplink signal meets a requirement of receive power of the base station after arriving at the base station (Evolved NodeB, eNB). When a TPC command sent by a base station is carried on a physical downlink control channel (PDCCH) whose format is a downlink control information format 3/3A (DCI format 3/3A), UE cannot acquire a TPC command of an uplink signal at any moment and can acquire the TPC command of the uplink signal only according to a time sequence relationship predefined by a standard, because currently a strict time sequence relationship exists between the DCI format 3/3A and the uplink signal indicated by the DCI format 3/3A.
Therefore, in a scenario in which a dynamic TDD uplink-downlink subframe configuration is applied, when a subframe that sends the DCI format 3/3A is dynamically configured as an uplink subframe, UE cannot acquire a TPC command required for sending an uplink signal. As a result, a base station fails to receive the uplink signal.